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US 5,473,727 AGranted
Voice encoding method and voice decoding method
AssigneeSony Corporation
InventorsMasayuki Nishiguchi, Ryoji Wakatsuki, Jun Matsumoto, Shinobu Ono
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AssigneeSony Corporation
InventorsMasayuki Nishiguchi, Ryoji Wakatsuki, Jun Matsumoto, Shinobu Ono
Estimating the term…
A compressed digital speech signal is encoded to provide a transmission error-resistant transmission signal. The compressed speech signal is derived from a digital speech signal by performing a pitch search on a block obtained by dividing the speech signal in time to provide pitch information for the block. The block of the speech signal is orthogonally transformed to provide spectral data, which is divided by frequency into plural bands in response to the pitch information. A voiced/unvoiced sound discrimination generates voiced/-unvoiced (V/UV) information indicating whether the spectral data in each of the plural bands represents a voiced or an unvoiced sound. The spectral data in the plural bands are interpolated to provide spectral amplitudes for a predetermined number of bands, independent of the pitch. Hierarchical vector quantizing is applied to the spectral amplitudes to generate upper-layer indices, representing an overview of the spectral amplitudes, and lower-layer indices, representing details of the spectral amplitudes. CRC error detection coding is applied to the upper-layer indices, the pitch information, and the V/UV information to generate CRC codes. Convolution coding for error correction is applied to the upper-layer indices, the higher-order bits of the lower-layer indices, the pitch information, the V/UV information, and the CRC codes. The convolution-coded quantities from two blocks of the speech signal are then interleaved in a frame of the transmission signal, together with the lower-order bits of the respective lower-layer indices.
A method for encoding a compressed digital signal to provide a transmission signal resistant to transmission channel errors, the compressed digital signal being derived from a digital speech signal by dividing the digital speech signal in time to provide a signal block, orthogonally transforming the signal block to provide spectral data on the frequency axis, and using multi-band excitation to determine from the spectral data whether each of plural bands obtained by a pitch-dependent division of the spectral data in frequency represents one of a voiced (V) and an unvoiced (UV) sound, and to derive from the spectral data a spectral amplitude for each of a predetermined number of bands obtained by a fixed division of the spectral data by frequency, each spectral amplitude being a component of the compressed signal, the method comprising the steps of:
A method for decoding a transmission signal that has been coded to provide resistance to transmission errors, the transmission signal including frames composed of pitch information, voiced/unvoiced (V/UV) information for each of plural bands, an upper-layer index and lower-layer indices generated by hierarchical vector quantizing, the lower-layer indices including upper-order bits and lower-order bits, the pitch information, the V/UV information, and the upper-layer index being coded to generate codes for cyclic redundancy check (CRC) error detection, the pitch information, the V/UV information, the upper-layer index, the upper-order bits of the lower-layer indices, and the CRC codes being convolution-coded, the method comprising the steps of:
Dependencies are inferred from the claim text.